1. Field
This disclosure relates to an image display device, specifically to an image display device displaying a three dimensional (hereinafter 3D) image without field-of-view overlapping effects and chromatic dispersion.
2. Description of the Related Art
Glasses-free 3D displays, which do not require special glasses, are being developed. However, such displays with two views impose limitations on the region within which a 3D image may be seen. Multiple or hypermultiple views have been introduced to improve this problem, but they require very high display resolution, or high speed display devices, preventing commercial use. Moreover, the barrier method or the dynamic barrier method for virtual reality, which provide 3D images corresponding at a viewer's position using a static parallax barrier, also have problems caused by the variation of resolution depending on situations. Further, the barrier method is not able to provide two dimensional (hereinafter 2D) images. Further, the dynamic barrier method requires an additional liquid crystal panel with great precision.
In all cases regarding two, multiple, or hypermultiple views using the static parallax barrier method of a glasses-free 3D display, a region in which a plurality of views coexist may develop, which is called a field-of-view overlapping effect. At the region, a three dimensional effect is eliminated or substantially deteriorated in principle, which is called the problem of a field-of-view overlapping effect.
FIG. 1 illustrates a 3D display device with two views using a parallax barrier. This method is associated with the problems of chromatic dispersion and field-of-view overlapping effects.
The 3D image display device includes a flat image display device 101 and a parallax barrier 102. The flat image display device 101 is composed of pixels in which red, green, and blue are arranged, respectively, in this order. The image transmitted through the parallax barrier 102 is represented at the field of view 103 of left and right eyes. In the flat image display device 101, the vertical lines of pixels in the left and right images vary alternatingly in the horizontal direction (104), and all pixels in the perpendicular direction operate simultaneously (105).
Reference numerals 106 to 108 represent the paths of rays corresponding to the left eye in order of blue (B), green (G), and red (R). Reference numerals 109 to 111 represent the paths of rays corresponding to the right eye in the same order.
Reference numerals 112 to 114 indicate the distribution and the brightness of each unit of color components for the view corresponding to the left eye, and reference numerals 115 to 117 represent those of each unit of color components for the view corresponding to the right eye. RGB image signals for left and right eyes should represent the same distributions and brightnesses with respect to each other for the same view, but may be dispersed as illustrated in FIG. 1, which is called chromatic dispersion.
Further, a region 118 in which each of views for left and right eyes overlap, i.e. field-of-view overlapping, may be formed.
Usually, in case that a static parallax barrier is used for two views, the problem of chromatic dispersion, i.e. the phenomenon that each rays of pixels disperses when transmitting the barrier, occurs to prevent colors from being accurately represented. Because the element representing color within each pixel is not uniformly distributed in the whole area, but is divided by particular zones, relative positions of rays of pixels are different from each other when the rays traverse the barrier. This difference leads to chromatic dispersion, which aggravates field-of-view overlapping effects.
Chromatic dispersion and field-of-view overlapping effects are found also in a method using lenses. It is because a parallax barrier is to replace lenses.